Interconnections of implantable lead conductors and electrodes and reinforcement therefor

ABSTRACT

An implantable lead comprises a lead body extending from a lead proximal end portion to a lead distal end portion. The lead body includes one or more longitudinally extending lumens. A conductor is received in, and extends along, a lumen. In varying examples, the implantable lead further comprises a tubular electrode co-axial with, and overlying portions of, the lead body. In one example, a lumen wall is sized and shaped to urge an electrically conductive interposer coupled with the conductor toward an inner surface of the electrode. In another example, a ring member is disposed within a lumen and the conductor is drawn and coupled thereto. In yet another example, an electrically conductive connector couples a first and a second conductor via grooves or threads. In a further example, an axial support member couples a distal end electrode and the lead body. Methods associated with the foregoing are also discussed.

TECHNICAL FIELD

This patent document pertains generally to implantable leads for linkingimplantable medical devices with selected body tissue to be sensed orstimulated by such devices. More particularly, but not by way oflimitation, this patent document pertains to interconnections ofimplantable lead conductors and electrodes and reinforcement therefor.

BACKGROUND

Implantable leads represent the electrical link between an implantablemedical device (often referred to simply as “IMD”) and a subject'scardiac or other tissue, which is to be sensed or stimulated. Animplantable lead may include a single or multiple conductors that areconnected to an electrode or an electrode assembly at a leadintermediate portion or a lead distal end portion. A connector isincluded at a lead proximal end portion to form an electrical connection(via the conductor(s)) between the electrode or electrode assembly andthe IMD.

Over the years, a large number of different mechanisms and methods forinterconnecting conductors and electrodes have been proposed. It isdesirable that such connections between the conductor and the electrodeprovide a highly reliable electrical connection, with good mechanicalproperties including high tensile strength. It is also desirable thatsuch connections allow for the lead assembly itself to retain a highdegree of tensile strength through the area of the electrode. This isbecause cardiac (and other) leads undergo considerable stresses due torepetitive flexing caused by, for example, the motion of a beating heartand forces applied to the lead during an implantation, repositioning, orlead extraction procedure.

Typically, conductors in commercially marketed pacing and defibrillationleads have taken the form of single or multi-filar wire coils. Recently,there has been a high level of interest in designing leads having leadbodies with a reduced size (i.e., lead body diameter) or additionalelectrodes. One way to reduce to lead body size is to employ, at leastin part, stranded wire conductors such as cables, in the place of coiledwire conductors. However, such stranded wire conductors present newchallenges not faced by the use of coiled wire conductors. As oneexample, it has been a great challenge to electrically and reliablyconnect a small multi-strand conductor cable (often times having a cableouter diameter on the order of thousandths of an inch) to a ringelectrode or a multi-filar shock coil electrode. Being of such smallsize, the connection is a very difficult one to make and fragile, ifmade incorrectly.

With respect to single or multi-filar wire coiled conductors, when suchconductors are used to electrically connect a distal (tip) electrode tothe IMD, portions of the distal electrode typically are polymer bonded(e.g., via an adhesive) to provide additional axial strength to theelectrode. However, even with such additional polymer-provided strength,the distal electrode/lead body connection may still fall short of theaxial strength necessary to resist permanent deformation or in order topass industry standards (e.g., CEN/CENELEC 45502-2-1, § 23.3).

SUMMARY

An implantable lead comprises a lead body extending from a lead proximalend portion to a lead distal end portion, with a lead intermediateportion therebetween. The lead body includes one or more longitudinallyextending lumens. A conductor is received in, and extends along, a firstlumen. An electrically conductive interposer, coupled with theconductor, is also received, at least in part, in the first lumen. Theimplantable lead further comprises a tubular electrode that is co-axialwith, and overlays portions of, the leady body. In varying examples, aportion of a first lumen wall compressively urges the interposer towardan inner surface of the tubular electrode.

Another implantable lead comprises a lead body extending from a leadproximal end portion to a lead distal end portion. The lead bodyincludes an internal longitudinally extending lumen. A ring member isdisposed within the lumen such that a portion of the ring member extendsthrough a hole or slit (collectively termed “aperture”) in a lumen wall.A conductor is received in, and extends along, the lumen. A distal endportion of the conductor is drawn adjacent to an outer surface of thering member and electrically coupled thereto. The implantable leadfurther comprises a tubular electrode that is co-axial with, andoverlays portions of, the lead body. The tubular electrode iselectrically coupled with the conductor via the ring member.

Yet another implantable lead comprises a lead body extending from a leadproximal end portion to a lead distal end portion, with at least one ofa lumen or a slit therein. The lead comprises a first and a secondconductor along with an electrically conductive connector. Theelectrically conductive connector includes a first end portion coupledwith the first conductor and a second end portion coupled with thesecond conductor. The electrically conductive connector is received inthe lumen or slit of the lead body. The lead further comprises asecuring member disposed and deformed around a portion of one or both ofthe first conductor of the second conductor.

A further implantable lead comprises a lead body extending from a leadproximal end portion to a lead distal end portion, with a leadintermediate portion therebetween. The lead body includes at least afirst and a second internal longitudinally extending lumens. A conductoris received in, and extends along, the first lumen and electricallycouples to a distal electrode at the lead distal end portion. An axialsupport member is received in the second lumen and extends from an axialsupport member proximal end portion to an axial support member distalend portion. A first retaining member engaged with the lead body iscoupled with the axial support member proximal end, while a secondretaining member engaged with the distal electrode is coupled with theaxial support member distal end.

The leads and methods described herein provide numerous advantages overconventional lead designs including secure electrical and mechanicalconnection between a conductor, such as a small multi-strand conductorcable, and an electrode (e.g., a ring electrode or a multi-filar shockcoil electrode). In addition, the leads and methods provide axialreinforcement between a distal electrode and a lead body. Furthermore,the leads and methods allow for the creation of a small-sized lead(e.g., sub-5 French), which advantageously provides for easier anddeeper lead delivery and lower sensing/stimulating thresholds. In onesuch example, the present leads and methods provide a small-sized leadwith multiple conductors and electrodes. Multiple conductors andelectrodes allow for electrode switching to prevent extra bodily tissuestimulation and optimize a variety of other sensing/stimulating relatedparameters (e.g., parameters relating to the selection ofelectrodes/vectors with the best thresholds, or optimizing hemodynamics)as further described in Hansen, et al., U.S. Patent Application titled“MULTI-SITE LEAD/SYSTEM USING A MULTI-POLE CONNECTION AND METHODSTHEREFOR,” Ser. No. 11/230,989, filed Sep. 20, 2005, which is herebyincorporated by reference in its entirety.

Several other advantages are also made possible by the present leads andmethods. In some examples, the leads and methods reduce or eliminate thereliance on adhesives to couple a conductor to an electrode.Advantageously, by reducing or eliminating reliance on adhesives,manufacturing efficiency can be increased (e.g., may not need to waitfor adhesives to cure), and conductor/electrode joint failure caused byadhesive bond strength decreasing over time (e.g., due to reactions withbodily fluids or improper adhesive preparation) can be reduced oreliminated. These and other examples, aspects, advantages, and featuresof the leads and methods described herein will be set forth in part inthe detailed description, which follows, and in part will becomeapparent to those skilled in the art by reference to the followingdescription of the present leads and methods, and drawings or bypractice of the same.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsdescribe similar components throughout the several views. The drawingsillustrate generally, by way of example, but not by way of limitation,various embodiments discussed in this patent document.

FIG. 1 is a schematic view illustrating an implantable lead system andan environment in which the lead system may be used, as constructed inaccordance with at least one embodiment.

FIG. 2A is a schematic view illustrating an implantable lead system fordelivering or receiving signals to and from a heart, as positioned andconstructed in accordance with at least one embodiment.

FIG. 2B is a schematic view illustrating an implantable lead system fordelivering or receiving signals to and from a heart, as positioned andconstructed in accordance with at least one embodiment.

FIG. 3 is a plan view of an implantable lead, as constructed inaccordance with at least one embodiment.

FIG. 4 is a cross-sectional view illustrating an implantable lead, asconstructed in accordance with at least one embodiment.

FIG. 5 is a cross-sectional view illustrating a portion of animplantable lead, as constructed in accordance with at least oneembodiment.

FIG. 6A is a cross-sectional view of an implantable lead taken alongline 6A-6A of FIG. 5, as constructed in accordance with at least oneembodiment.

FIG. 6B is a cross-sectional view illustrating a portion of animplantable lead, as constructed in accordance with at least oneembodiment.

FIG. 6C is a cross-sectional view of an implantable lead taken alongline 6A-6A of FIG. 5, as constructed in accordance with at least oneembodiment.

FIG. 6D is a cross-sectional view of an implantable lead including anurging member taken along line 6A-6A of FIG. 5, as constructed inaccordance with at least one embodiment.

FIG. 7A is a cross-sectional view illustrating a portion of animplantable lead and an urging member, as constructed in accordance withat least one embodiment.

FIG. 7B is a cross-sectional view illustrating a portion of animplantable lead, as constructed in accordance with at least oneembodiment.

FIG. 8A is a cross-sectional view illustrating a portion of animplantable lead, as constructed in accordance with at least oneembodiment.

FIG. 8B is a cross-sectional view of an implantable lead taken alongline 8B-8B of FIG. 8A, as constructed in accordance with at least oneembodiment.

FIG. 9 is a schematic view illustrating an electrically conductiveconnector, as constructed in accordance with at least one embodiment.

FIG. 10A is a cross-sectional view illustrating a portion of animplantable lead, as constructed in accordance with at least oneembodiment.

FIG. 10B is a cross-section view of an implantable lead taken along line10B-10B of FIG. 1A, as constructed in accordance with at least oneembodiment.

FIG. 11 is a flow diagram illustrating a method of manufacturing animplantable lead, as constructed in accordance with at least oneembodiment.

FIG. 12 is a flow diagram illustrating another method of manufacturingan implantable lead, as constructed in accordance with at least oneembodiment.

DETAILED DESCRIPTION

The following detailed description includes references to theaccompanying drawings, which form a part of the detailed description.The drawings show, by way of illustration, specific embodiments in whichthe present leads and methods may be practiced. These embodiments, whichare also referred to herein as “examples,” are described in enoughdetail to enable those skilled in the art to practice the present leadsand methods. The embodiments may be combined or varied, otherembodiments may be utilized or structural or logical changes may be madewithout departing from the scope of the present leads and methods. It isalso to be understood that the various embodiments of the present leadsand methods, although different, are not necessarily mutually exclusive.For example, a particular feature, structure or characteristic describedin one embodiment may be included within other embodiments. Thefollowing detailed description is, therefore, not to be taken in alimiting sense, and the scope of the present leads and methods aredefined by the appended claims and their equivalents.

In this document the terms “a” or “an” are used to include one or morethan one; the term “or” is used to refer to a nonexclusive or, unlessotherwise indicated; and the term “subject” is used synonymously withthe term “patient.”

Leads and methods discussed herein advantageously provide for secureelectrical and mechanical connections between a conductor and anelectrode or a conductor and another conductor, while further providinga small lead body diameter. In one example, a lead includes a (cable)conductor/electrode connection design using the compressive or elasticnature of a (polymer) lead body in conjunction with an appropriately(larger) sized electrically conductive interposer (e.g., metallic tube).In another example, a lead includes a (coil) conductor/ electrodeconnection design using a ring member. In yet another example, a leadincludes a conductor/conductor connection design using an electricallyconductive connector couplable with a first conductor on a first end andcouplable with a second conductor on a second end. In a further example,a lead includes an axial support member to reinforce a connectionbetween a distal electrode and (a portion of) the lead body.

Turning now to the drawings, and initially to FIG. 1, which illustratesa lead system 100 and an environment 106 (e.g., subcutaneous pocket madein the wall of a subject's chest, abdomen, or elsewhere) in which leadsystem 100 may be used. In varying examples, lead system 100 may be usedfor delivering or receiving electrical pulses or signals to stimulate orsense a heart 108 of a subject. As shown in FIG. 1, lead system 100includes an implantable medical device (referred to as “IMD”) 102 and animplantable lead 104. IMD 102 includes a source of power as well as anelectronic circuitry portion. In this example, IMD 102 is abattery-powered device that senses intrinsic signals of heart 108 andgenerates a series of timed electrical discharges. IMD 102 genericallyrepresents, but is not limited to, cardiac rhythm management devices(referred to as “CRM devices”) such as pacers, cardioverters,biventricular/cardiac resynchronization paces, defibrillators, andsensing instruments.

FIGS. 2A-2B are schematic views of a lead system 100 including an IMD102 and at least one lead 104. Lead 104 includes a lead body 202 whichextends from a lead proximal end portion 204, where it is coupled withIMD 102. Lead 104 extends to a lead distal end portion 206, which iscoupled with a portion of a heart 108 (e.g., via entanglement, lodging,or helical fixation), when implanted. Lead distal end portion 206includes at least one electrode 208A, 208B, 208C, 208D that electricallycouples lead 104 with heart 108. At least one conductor 602 (cable) or604 (coil) (both shown in FIG. 6A), electrically couple electrodes 208A,208B, 208C, 208D with lead proximal end portion 204 and, thus IMD 102.The conductors 602, 604 (FIG. 6A) carry electrical current and pulses orshocks between IMD 102 and electrodes 208A, 208B, 208C, 208D. Lead 104may be installed using both over-the-wire techniques or non-over-thewire techniques (i.e., stylet driven techniques or catheter deliveredtechniques).

In the examples shown in FIGS. 2A-2B, lead 104 is a multi-electrode leadthat includes a proximal electrode 208A, two intermediate electrodes208B, 208C, and a distal electrode 208D. Each of the electrodes 208A,208B, 208C, 208D may be ring electrodes or multi-filar shock coilelectrodes and are independently electrically connected to a separatecorresponding electrically conductive terminal within a header 210 ofIMD 102. Header 210 is affixed to a hermetically sealed housing 212,which may be formed from a conductive metal such as titanium, and whichcarries, at least portions of, the electronic circuitry of IMD 102. Inthis example, header 210 includes a header electrode 214 and housing 212includes a housing electrode 216, both of which may be used in one ormore electrode configurations for sensing or stimulating heart 108 asfurther described in Hansen, et al., U.S. Patent Application titled“MULTI-SITE LEAD/SYSTEM USING A MULTI-POLE CONNECTION AND METHODSTHEREFOR,” Ser. No. 11/230,989, filed Sep. 20, 2005.

As shown in FIG. 2A, lead distal end portion 206 of lead 104 is disposedin a right ventricle 250 of heart 108. FIG. 2A further illustrates thatlead 104 may include at least one preformed biased portion to urge oneor more electrodes thereon against a septal wall 252 for pacing orsensing of the same. Referring now to FIG. 2B, lead distal end portion206 is disposed in a coronary vein 256 after being guided through acoronary sinus ostium and a coronary sinus 254. Placing lead 104 in acoronary branch vein (e.g., 256) on a left ventricle 260 has been foundto be a suitable means for delivering stimulation therapy to a subjectsuffering from congestive heart failure without having to position lead104 within left ventricle 260. Other lead 104 placements besides thoseillustrated in FIGS. 2A-2B are also possible without departing from thescope of the present leads and methods.

FIG. 3 illustrates a plan view of an implantable lead 104. As shown,lead 104 includes a lead body 202 extending from a lead proximal endportion 204 to a lead distal end portion 206 and having an intermediateportion 302 therebetween. In one example, lead body 202 comprisesbiocompatible tubing such as medical grade polyurethane. In anotherexample, lead body 202 comprises medical grade silicone rubber or otherthermoplastic or polymer known in the art to be suitable for use inleads. As discussed above in association with FIG. 1, a lead system 100includes, among other things, lead 104 for electrically coupling an IMD102 (FIG. 1) to bodily tissue, such as a heart 108 (FIG. 1), which is tobe excited (i.e., stimulated) or sensed by one or more electrodes 208A,208B, 208C, 208D. It should also be understood that the lead 104 mayalso include means for sensing other physiological parameters, such aspressure, oxygen saturation, temperature, or the like. Lead 104 mayinclude electrodes 208A, 208B, 208C, 208D only, other physiologicsensors, drug collars 306, or a combination thereof.

In the example shown in FIG. 3, lead proximal end portion 204 includesfour terminal connections 304A, 304B, 304C, 304D disposed therealong.Similarly, lead intermediate portion 302 or lead distal end portion 206include four electrodes 208A, 208B, 208C, 208D disposed therealong.Electrodes 208A, 208B, 208C, 208D are each adapted to sense or stimulateheart 108 (FIG. 1) and are electrically coupled to terminal connections304A, 304B, 304C, 304D via at least four conductors 602 (cable) or 604(coil) (both shown in FIG. 6A) contained within lead body 202, such asin one or more internal longitudinally extending lumens 606, 608, 610,612 (FIG. 6A). Lead proximal end portion 204 and terminal connections304A, 304B, 304C, 304D disposed therealong are sized and shaped tocouple to a multi-pole connector cavity, which may be incorporated intoa header 210 (FIGS. 2A-2B) of IMD 102 (FIGS. 2A-2B). It is through thecoupling between lead proximal end portion 204 and the multi-polarconnector cavity that electrodes 208A, 208B, 208C, 208D are electricallycoupled to electronic circuitry of IMD 102.

Advantageously, the present leads and methods provide for secureelectrical and mechanical connection between conductors 602 (cable) or604 (coil) (both shown in FIG. 6A) and electrodes 208A, 208B, 208C, 208Dwhile maintaining a small lead body 202 sized (i.e., diameter), such assub-5 French. In one example, as discussed in greater detail inassociation with FIGS. 6A and 6B, lead 104 includes aconductor/electrode connection design using the compressive nature oflead body 202 in conjunction with an appropriately sized electricallyconductive interposer (e.g., electrically conductive tube) 614 (FIG. 6A)or similar element. In another example, as discussed in greater detailin association with FIGS. 7A-8B, lead 104 includes a conductor/electrodeconnection design using a ring member 706 in conjunction with a securingmember 702 (FIG. 7A) deformable using, for example, crimping, swaging,welding, or brazing techniques. In yet another example, as discussed ingreater detail in association with FIG. 9, lead 104 includes aconductor/conductor connection design using an electrically conductiveconnector 902 (FIG. 9) couplable with a first conductor on a first endand couplable with a second conductor on a second end. In a furtherexample, as discussed in greater detail in association with FIGS. 10Aand 10B, lead 104 includes an axial support member 1002 to reinforce aconnection between a distal electrode 208D and (a portion of) lead body202.

FIGS. 4, 5, 8A, and 10A illustrate cross-sectional views of animplantable lead 104 or portions thereof. Specifically, FIG. 4illustrates a cross-sectional view of an implantable lead 104 extendingfrom a lead proximal end portion 204 to a lead distal end portion 206and having a lead intermediate portion 302 therebetween. FIG. 5 is across-sectional view illustrating a lead distal end portion 206 or alead intermediate portion 302 of an implantable lead 104 (FIG. 4) ingreater detail. FIG. 8A is a cross-section view illustrating a leadproximal end portion 204 of an implantable lead 104 (FIG. 4) in greaterdetail. FIG. 10A is a cross-sectional view illustrating a lead distalend portion 206 or a lead intermediate portion 302 of an implantablelead 104 (FIG. 4) in greater detail.

FIG. 6A illustrates a cross-sectional view taken along line 6A-6A ofFIG. 5 of an implantable lead 104 (FIG. 4). FIG. 6A shows, among otherthings, a conductor/electrode connection design 600 using thecompressive nature of a lead body 202 in conjunction with anappropriately sized (i.e., slightly larger than a size of a receivinglumen 610) electrically conductive interposer (e.g., electricallyconductive tube) 614, and further in conjunction with an interposerexposing hole or slit (collectively termed “aperture”) 650 in a wall oflumen 610. In this example, lead body 202 includes four internallongitudinally extending lumens 606, 608, 610, 612 that allow one ormore conductors 602 (cable), 604 (coil) to be received in, and extendalong, lead 104 (FIG. 4). In one example, wall portions of at least onelumen (e.g., 610) are sized and shaped to urge an electricallyconductive interposer 614 toward an inner surface 616 of a tubularelectrode 618 co-axial with, and overlying portions of, lead body 202through hole or slit 650. When the (slightly larger than lumen 610)electrically conductive interposer 614 is inserted into lumen 610, thewall portions of the lumen deform into an urging shape, such as thatdepicted by phantom line 630.

In this example, electrically conductive interposer 614 is a metal tubethat is coupled with conductor 602 and inserted into the at least onelumen (e.g., 610) having an urging size and shape. The coupling betweenelectrically conductive interposer 614 and conductor 602 may beperformed by, among other techniques, crimping, swaging, welding, orbrazing. In one such example, as shown in FIG. 6C, electricallyconductive interposer 614 is crimped to conductor 602 (FIG. 6B) suchthat an outer surface 620 of tube 614 mates, in part, with an innersurface 616 of tubular electrode 618 (FIG. 6B) (i.e., R₁, representing aradius from a lead body 202 center to outer surface 620, isapproximately equal to R₂, representing a radius from the lead body 202center to inner surface 616). This ensures intimate contact and anadequate fitting for welding 622 tubular electrode 618 to electricallyconductive interposer 614. After being inserted in lumen 610 and urgedtoward inner surface 616 of tubular electrode 618 (by wall portions oflumen 610) through hole or slit 650, electrically conductive interposer614 may be coupled to tubular electrode 618, such as by spot or laserwelding 622 (see also FIG. 6B), brazing, or using a conductive adhesive.

FIG. 6B is a cross-sectional view illustrating a lead distal end portion206 or a lead intermediate portion 302 of an implantable lead 104.Specifically, FIG. 6B illustrates one or more spot or laser welding 622that may be made between an electrically conductive interposer 614 and atubular electrode 618, in accordance with at least one embodiment of aconductor/electrode connection design 600. As shown in FIG. 6B, wallportions of a lumen 610 in lead body 202 are sized and shaped to urgeelectrically conductive interposer 614 toward an inner surface 616 oftubular electrode 618 through hole or slit 650. As also shown,electrically conductive interposer 614 is coupled with a conductor 602,such as by crimping, swaging, welding, or brazing. Prior to thecrimping, swaging, welding, or brazing, most of the insulating coating624 on a distal end of conductor 602 may need to be removed to allow forelectrical communication between electrically conductive interposer 614and conductor 602. Although not shown in FIG. 6B, weld 622 may be acontinuous weld between interposer 614 and electrode 618.

FIG. 6D illustrates a removable expanding mandrel 652 surrounded by asplit cylinder 654, both of which may be inserted into (coil receiving)lumen 612 (FIG. 6A) of lead body 202 to urge electrically conductiveinterposer 614 toward inner surface 616 of tubular electrode 618. In oneexample, movement of mandrel 652 in direction 656 causes split cylinder654 to expand in directions 658A, 658B, which in turn urges lead body202 against interposer 614 in a direction toward electrode 618.

FIGS. 7A and 7B illustrate a cross-sectional view of a lead distal endportion 206 (FIG. 5) or a lead intermediate portion 302 of animplantable lead 104 (FIG. 4). FIGS. 7A and 7B show, among other things,a conductor/electrode connection design 700 using a ring member 706.

In the example of FIG. 7A, a lead body 202 includes at least oneinternal longitudinally extending lumen 612 that allows one or moreconductors 604, such as a coil conductor, to be received in, and extendalong, lead 104 (FIG. 4). In one example, a distal end portion ofconductor 604 extends along lead 104 (FIG. 4) to a location adjacent toan outer surface 704 of ring member 706, which is disposed within lumen612, and coupled thereto. As shown, a portion of ring member 706 extendsthrough a hole or slit 750 in a wall of lumen 612.

The distal end portion of conductor 604 may be coupled to ring member706 using one or more of a variety of techniques. In one example,conductor 604 is coupled to ring member 706 by first urging conductor604 over a slightly larger diameter ring member 706. In another example,a securing member 702 is disposed around the distal portion of conductor604 and ring member 706 and deformed, such as by crimping, (rotary)swaging, welding, or brazing. Rotary swaging is a metal forming processfor the diametrical reduction of annular securing members, such as bars,tubes, wires, etc. In this example, securing member 702 is deformed overthe distal end portion of conductor 604 thereby coupling the conductor604 to ring member 706. As shown in FIG. 7A, a tubular electrode 618co-axial with, and overlying portions of, lead body 202 is electricallycoupled with conductor 604 via (conductive) securing member 702 and/or(conductive) ring member 706. In one example, a removable preformedmandrel 752 is used to urge ring member 706 toward electrode 618 priorto coupling between the same. As shown, mandrel 752 includes a preformedbend 760 to urge ring member 706 toward electrode 618.

In the example of FIG. 7B, an adhesive 708 and one or more grooves (orthreads) 710 are used in conjunction with a securing member 702 tocouple a conductor 604 to a ring member 706. As discussed above, aftersecuring member 702 is positioned over a distal end portion of conductor604 and ring member 706, securing member 702 may then deformed to snuglysecure conductor 604 to ring member 706. The deformation decreases theinternal diameter of securing member 702 thereby reconfiguring a shapeof securing member 702 and pinching adhesive 708 (which may be insertedfor additional coupling strength) over conductor 604 and into the one ormore grooves (or threads) 710 in ring member 706. Grooves (or threads)710 may be used to provide additional axial strength at theconductor/electrode connection design 700. Adhesive 708 may be asuitable medical grade adhesive, such as silicone based adhesive, atwo-part adhesive, a conductive adhesive, or another similar adhesive.Adhesive 708 forms a secure mechanical bond between securing member702,conductor 604, and ring member 710. As shown in FIG. 7B, a tubularelectrode 618 co-axial with, and overlying portions of, lead body 202 iselectrically coupled with conductor 604 via (conductive) securing member702 and/or (conductive) ring member 706.

FIG. 8B is a cross-sectional view of an implantable lead 104 (FIG. 4)taken along line 8B-8B of FIG. 8A. FIG. 8B shows a conductor/electrodeconnection design 700 using a securing member 702 deformable using, forexample, rotary swaging. In this example, securing member 702 isdeformed over a conductor 604 to couple conductor 604 to a ring member706.

FIG. 9 illustrates an electrically conductive connector 902 for use in aconductor/conductor connection design 900. Conductor/conductorconnection design 900 may be used to advantageously couple a first(coil) conductor 604A to a (coil) second conductor 604B within a leadbody 202 (FIG. 3) providing, among other things, different mechanical orelectrical properties or cost savings (e.g., a first conductor may beformed from an expensive material and a second, longer conductor may beformed from a less expensive material).

Electrically conductive connector 902 includes a first end portion 904couplable with first conductor 604A and a second end portion 906couplable with second conductor 604B. In the example shown, electricallyconductive connector 902 includes one or more internal grooves (orthreads) 908. In another example, electrically conductive connector 902includes one or more external grooves (or threads). Conductors 604A,604B may be further secured (i.e., in addition to the one or moregrooves) to electrically conductive connector 902 by rotary swaging,laser or resistance welding, brazing, mechanical swaging, or crimping.In one example, conductors 604A, 604B are further secured toelectrically conductive connector using a securing member disposed anddeformed around a portion of the conductors by rotary swagingtechniques. In examples in which one or both of first conductor 604A orsecond conductor 604B are coupled via one or more external grooves (suchas those associated with screw threads), shrink tubing or acompressive/elastic lead body 202 (FIG. 6A) may be used to furthersecure such conductors to connector 902.

FIG. 10A illustrates a cross-sectional view of a lead distal end portion206 of an implantable lead 104 (FIG. 4). FIG. 10A shows, among otherthings, a reinforcement design 1000 for increasing the axial strengthbetween a distal electrode (e.g., 208D) and a lead body 202. In thisexample, lead body 202 includes at least a first 1004 and second 1006internal longitudinally extending lumens. A conductor 604 is receivedin, and extends along, first lumen 1004 and electrically couples todistal electrode 208D at a distal end thereof.

To provide additional axial strength to the distal electrode208D/conductor 604 connection joint, lead 104 (FIG. 4) may include anaxial support member 1002 received in the second lumen 1006. Axialsupport member 1002 extends from an axial support member proximal endportion 1008 to an axial support member distal end portion 1010. Asshown, axial support member proximal end portion 1008 is coupled with afirst retaining member 1012, while axial support member distal endportion 1010 is coupled with a second retaining member 1014. Retainingmembers 1012, 1014 are engaged with lead body 202 and distal electrode208D, respectively, thereby providing the additional axial support tothe distal electrode/conductor joint.

Many options are possible for reinforcement design 1000. In one example,axial support member 1002 is a cable. In another example, first 1012 andsecond 1014 retaining members include at least one of a crimped tube, aswaged tube, a welded tube, or a brazed tube (i.e., a couplable tube).In one such example, distal electrode 208D is placed over an outersurface of the crimped or swaged tube and laser welded thereto. Inanother example, an outer diameter of first retaining member 1012 isgreater than a diameter of second lumen 1006 (see FIG. 10B). To makeroom for such larger retaining member 1012, lumen 1006 is cut or ablatedin the placement vicinity of member 1012. In such an example, distalelectrode 208D is held in place because first retaining member cannotslide through second lumen 1006 due to its larger size. In addition,lead body 202 may be fused around retaining member 1012 to providefurther retainment strength. In yet another example, a plug member 1016(e.g., a polyurethane filament) or other sealant means is inserted insecond lumen 1006 proximal to first retaining member 1012 and adhered tolead body 202 (e.g., by heat fusing techniques) to electrically isolatereinforcement member 1012 and electrode 208D from a more proximalconductor in a second lumen. In further examples, an outer surface ofdistal electrode 208D is isodiametric or non-isodiametric with an outersurface of lead body 202, or one or more knots are used in conjunctionwith one or both of the first and the second retaining members.

FIG. 10B is a cross-sectional view of an implantable lead 104 (FIG. 4)taken along line 10B-10B of FIG. 10A. FIG. 10B shows, among otherthings, an outer diameter of first retaining member 1012 greater than adiameter of second lumen 1006 of lead body 202 and covered by fusing ofthe same thereby precluding retaining member 1012 from being pulledthrough lumen 1006 without high force. As discussed above, axialsupporting member 1002 is coupled with first retaining member 1012 onaxial supporting member proximal end 1008 and coupled with secondretaining member 1014 (FIG. 10A) on axial supporting member distal end1010. As further discussed above, distal electrode 208D may be laserwelded (or otherwise secured) to second retaining member 1014 (FIG.10A). Accordingly, axial load placed on distal electrode 208D issupported, at least in part, by reinforcement design 1000. As also shownin FIG. 10B, a weld ring 1050 coupled to conductor 604 on an innersurface and fused to lead body 202 on an outer surface may also be usedto provide axial support to distal electrode 208D/conductor 604connection joint.

FIG. 11 is a flow diagram illustrating a method 1100 of manufacturing animplantable lead. At 1102, a lead body extending form a lead proximalend to a lead distal end is formed. Forming the lead body includesforming at least a first longitudinally extending lumen therein. Invarying examples, wall portions of the first lumen are sized and shapedto urge an appropriately (larger) sized element (e.g., an electricallyconductive interposer—see 1108) placed in the first lumen outward towarda tubular electrode co-axial with, and overlying portions of, the leadbody. At 1104, an interposer exposing hole or slit is cut or ablated ina first lumen wall (opposite the urging wall portions) to receive theinterposer and allow such element to electrically couple a conductor(see 1106) and the tubular electrode. At 1106, the conductor is drawninto and through the first lumen

At 1108, the electrically conductive interposer is inserted into thefirst lumen such that the conductor is located therewithin (i.e., the(tubular) interposer is slid onto at least a portion of the conductor).At 1110, the electrically conductive interposer is coupled to theconductor. This may initially include, among other things, removing aninsulative coating on an outer side of the conductor. In one example,the electrically conductive interposer is coupled to the conductor viacrimping, swaging, welding, or brazing. In one such example, theelectrically conductive interposer is crimped to the conductor such thatan outer surface of the electrically conductive interposer mates with (asized and shape of) an inner surface of the tubular electrode, therebyproviding a more conducive juncture for the process of 1112.

At 1112, the conductor is slightly pulled from a conductor proximal endor an interposer distal end is pushed into the exposing hole or slit sothat the interposer is fully within the outer boundaries of the leadbody. Optionally, at 1114, a removable expanding mandrel may be disposedinto a second lumen to urge the interposer outward toward the innersurface of the tubular electrode. At 1116, the interposer is coupled tothe inner surface of the tubular electrode via welding, brazing,conductive adhesives, or other suitable techniques.

FIG. 12 is a flow diagram illustrating another method 1200 ofmanufacturing an implantable lead. At 1202, a lead body extending from alead proximal end portion to a lead distal end portion and including aninternal longitudinally extending lumen is formed. At 1204, a hole orslit in a lumen wall is cut or ablated. At 1206, a ring member isdisposed within the lumen such that a portion of the ring member isinserted through the hole or slit in the lumen wall. At 1208, aconductor is drawn into and through the lumen such that a distal endportion of the conductor is adjacent the ring member.

The conductor may be coupled to the ring member using a variety oftechniques (see, e.g., 1210, 1216, and 1218). A first technique includesa securing member being disposed around the distal end portion of theconductor and the ring member (at 1210). Optionally, at 1212, one ormore grooves or threads may be formed on the ring member. At 1214, thesecuring member is deformed over the conductor for coupling purposes. Inone such example, portions of the securing member are pushed into orover the one or more grooves or threads. A second technique includesusing a conductive adhesive to couple the conductor to the ring member(at 1216). A third coupling technique includes forming one or moregrooves or threads on the ring member (at 1218) and urging the conductoronto the one or more grooves or threads (at 1220). Such urging may comeby way of the compressive nature of the lead body or a removablepreformed mandrel. In addition, the conductor may be coupled to the ringmember using only urging forces, such as the compressive nature of thelead body or through the use of the removable preformed mandrel.

At 1222, a tubular electrode co-axial with the lead body is overlaid onportions thereof In one example, the lead body is overlaid on portionsof the lead body such that a substantially smooth, uninterrupted surfaceat the interface of the tubular electrode and an outer surface of thelead body results. A smooth outer lead body surface may be desirable asit allows for easy passage of the lead through veins of a subject andfurther minimizes thrombus formation and the like.

Using various techniques, the tubular electrode is electrically coupledwith the conductor. In one example, the tubular electrode is coupledwith a portion of the ring member, which (as discussed above) may beelectrically coupled to the conductor. Such coupling may include one ormore of welding (at 1224), brazing (at 1224), or using a conductiveadhesive (at 1226). Portions of the ring member may be urged toward aninner surface of the tubular electrode using, for example, the preformedmandrel at 1228 or another urging means.

The leads and methods described herein provide numerous advantages overconventional lead designs including secure electrical and mechanicalconnection between a conductor, such as a small multi-strand conductorcable, and an electrode (e.g., a ring electrode or a multi-filar shockcoil electrode). In addition, the leads and methods provide axialreinforcement between a distal electrode and a lead body. Furthermore,the leads and methods allow for the creation of a smaller-sized lead(e.g., sub-5 French), which advantageously provides for easier anddeeper lead delivery and lower sensing/stimulating thresholds. In onesuch example, the present leads and methods provide a small-sized leadwith multiple conductors and electrodes.

Several other advantages are also made possible by the present leads andmethods. As one example, the leads and methods reduce or eliminate thereliance on adhesives to couple a conductor to an electrode.Advantageously, by reducing or eliminating reliance on adhesives,manufacturing efficiency can be increased (e.g., don't need to wait foradhesives to cure), and conductor/electrode joint failure caused byadhesive bond strength decreasing over time (e.g., due to reactions withbodily fluids or improper adhesive preparation) can be reduced oreliminated.

It is to be understood that the above description is intended to beillustrative, and not restrictive. It should be noted that the abovetext discusses, among other things, interconnections of implantable leadconductors and electrodes for use in cardiac situations; however, thepresent leads and methods are not so limited. Many other embodiments andcontexts, such as for non-cardiac nerve and muscle situations, will beapparent to those of skill in the art upon reviewing the abovedescription. The scope should, therefore, be determined with referenceto the appended claims, along with the full scope of equivalents towhich such claims are entitled.

1. An implantable lead comprising: a lead body extending from a leadproximal end portion to a lead distal end portion and having a leadintermediate portion therebetween, the lead body including one or morelongitudinally extending lumens; a conductor received in, and extendingalong, a first lumen; an electrically conductive interposer coupled withthe conductor, the interposer received, at least in part, in the firstlumen; a tubular electrode co-axial with, and overlying portions of, thelead body; and wherein a portion of a first lumen wall compressivelyurges the interposer, at least in part, toward an inner surface of thetubular electrode.
 2. The implantable lead as recited in claim 1,wherein the lead body further comprises an interposer exposing aperturein the first lumen wall disposed opposite the first lumen wall urgingportion.
 3. The implantable lead as recited in claim 1, wherein theinterposer is coupled with an inner surface of the tubular electrode. 4.The implantable lead as recited in claim 3, wherein the electricallyconductive interposer is crimped, swaged, welded, or brazed to theconductor.
 5. The implantable lead as recited in claim 1, wherein anouter surface of the interposer mates, in part, with the inner surfaceof the tubular electrode.
 6. The implantable lead as recited in claim 1,wherein the lead body comprises an elastic polymer.
 7. The implantablelead as recited in claim 1, wherein an outer surface of the tubularelectrode is substantially isodiametric with an outer surface of thelead body.
 8. A method of manufacturing an implantable lead, the methodcomprising: forming a lead body extending from a lead proximal endportion to a lead distal end portion and having a lead intermediateportion therebetween; forming one or more longitudinally extendinglumens within the lead body, including forming a first lumen having: alumen wall portion sized and shaped to urge an electrically conductiveinterposer toward an inner surface of a tubular electrode co-axial with,and overlying portions of, the lead body, and a lumen wall portioncomprising an interposer exposing aperture sized and shaped to allowelectrical connection between the interposer and the tubular electrode;drawing a conductor into and through the first lumen; inserting theinterposer, at least in part, into the first lumen through the exposingaperture, including placing the interposer over the conductor; andcoupling the interposer to the conductor.
 9. The method as recited inclaim 8, further comprising compression fitting the interposer to theinner surface of the tubular electrode.
 10. The method as recited inclaim 8, further comprising coupling the interposer to the inner surfaceof the tubular electrode.
 11. The method as recited in claim 10, whereincoupling the interposer to the inner surface of the tubular electrodeincludes welding or brazing the interposer to the tubular electrode. 12.The method as recited in claim 8, further comprising disposing aremovable expanding mandrel in a second lumen positioned adjacent thefirst lumen; and urging the interposer toward the inner surface of theelectrode through movement of the mandrel.
 13. The method as recited inclaim 8, wherein coupling the interposer to the conductor includescrimping, swaging, welding, or brazing.
 14. An implantable leadcomprising: a lead body extending from a lead proximal end portion to alead distal end portion and having a lead intermediate portiontherebetween, the lead body including an internal longitudinallyextending lumen; a ring member disposed within the lumen, a portion ofthe ring member extending through an aperture in a lumen wall; aconductor received in and extending along the lumen, a distal endportion of the conductor disposed adjacent to the ring member andelectrically coupled thereto; and a tubular electrode co-axial with andoverlying portions of the lead body, the tubular electrode electricallycoupled with the conductor via the ring member portion extending throughthe lumen wall.
 15. The implantable lead as recited in claim 14, furthercomprising a securing member disposed around the distal end portion ofthe conductor and the ring member, the securing member deformed over theconductor thereby coupling the conductor to the ring member.
 16. Theimplantable lead as recited in claim 15, wherein the securing memberincludes a crimped, swaged, welded, or brazed securing member.
 17. Theimplantable lead as recited in claim 14, wherein the ring memberincludes one or more grooves to which the distal end portion of theconductor is coupled.
 18. The implantable lead as recited in claim 14,further comprising an adhesive disposed between the conductor and thering member.
 19. The implantable lead as recited in claim 14, wherein aportion of the lumen wall compressively urges the ring member, at leastin part, through the aperture in the lumen wall toward the inner surfaceof the tubular electrode.
 20. The implantable lead as recited in claim14, wherein an outer surface of the tubular electrode is isodiametricwith an outer surface of the lead body.
 21. A method of manufacturing animplantable lead, the method comprising: forming a lead body extendingfrom a lead proximal end portion to a lead distal end portion and havinga lead intermediate portion therebetween, including forming alongitudinally extending lumen within the lead body; disposing a ringmember within the lumen, including inserting a portion of the ringmember through an aperture in a lumen wall; drawing a conductor into andthrough the lumen, including disposing a distal end portion of theconductor adjacent to the ring member; coupling the conductor to thering member; and overlying portions of the lead body with a tubularelectrode, the tubular electrode co-axial with the lead body andelectrically coupled with the conductor.
 22. The method as recited inclaim 21, wherein coupling the conductor to the ring member includesdisposing a securing member around the distal end portion of theconductor and the ring member; and deforming the securing member overthe conductor.
 23. The method as recited in claim 21, further comprisingforming one or more grooves on the ring member.
 24. The method asrecited in claim 23, wherein coupling the conductor to the ring memberincludes using the one or more grooves.
 25. The method as recited inclaim 21, wherein coupling the conductor to the ring member includesusing a conductive adhesive.
 26. The method as recited in claim 21,wherein forming the longitudinally extending lumen includes forming alumen wall sized and shaped to urge the ring member, at least in part,toward an inner surface of the tubular electrode.
 27. The method asrecited in claim 21, wherein electrically coupling the tubular electrodewith the conductor includes using a preformed mandrel to urge the ringmember, at least in part, toward an inner surface of the tubularelectrode.
 28. The method as recited in claim 21, wherein overlyingportions of the lead body with the tubular electrode includes forming asubstantially isodiametric surface at an interface of the tubularelectrode and an outer surface of the lead body.
 29. An implantable leadcomprising: a lead body extending from a lead proximal end portion to alead distal end portion and having a lead intermediate portiontherebetween, the lead body including at least one of a lumen or a slit;a first conductor and a second conductor; an electrically conductiveconnector having a first end portion coupled with the first conductorand having a second end portion coupled with the second conductor, theconnector received in the lumen or the slit; and a securing memberdisposed around a portion of one or both of the first conductor or thesecond conductor, the securing member deformed over the conductorthereby coupling the conductor to the connector.
 30. The implantablelead as recited in claim 29, wherein one or both of the first endportion or the second end portion include one or more grooves to whichthe first or second conductor are coupled.
 31. The implantable lead asrecited in claim 29, wherein the one or more grooves are disposed on aninner surface of the connector.
 32. The implantable lead as recited inclaim 29, wherein the one or more grooves are disposed on an outersurface of the connector.
 33. An implantable lead comprising: a leadbody extending from a lead proximal end portion to a lead distal endportion and having a lead intermediate portion therebetween, the leadbody including at least a first and a second internal longitudinallyextending lumens; a conductor received in, and extending along, thefirst lumen; a distal electrode electrically coupled to the conductor;an axial support member received in the second lumen, the axial supportmember extending from an axial support member proximal end portion to anaxial support member distal end portion; wherein the axial supportmember proximal end portion is coupled with a first retaining member andthe axial support member distal end portion is coupled with a secondretaining member; and wherein the first retaining member is engaged withthe lead body and the second retaining member is engaged with the distalelectrode.
 34. The implantable lead as recited in claim 33, wherein thefirst retaining member or the second retaining member includes acouplable tube.
 35. The implantable lead as recited in claim 34, whereinan outer diameter of the first or the second retaining member is greaterthan a diameter of the second lumen.
 36. The implantable lead as recitedin claim 33, wherein the lead body is fused or bonded adjacent the firstor the second retaining member.
 37. The implantable lead as recited inclaim 33, wherein the second lumen is sealed proximal to the firstretaining member to electrically isolate the first retaining member froma second lumen-disposed conductor.